1. Field of the Invention
The invention relates to a bonding apparatus for electronic devices, and in particular to a handler station for temporary storage and/or manipulation of electronic devices prior to and subsequent to bonding, such as wire bonding or die bonding.
2. Background and Prior Art
In the process of forming a semiconductor integrated circuit package, a series of steps are taken to assemble various components to form a finished package, such as die bonding and wire bonding. Die bonding refers to the attachment of a semiconductor die to a carrier, such as a leadframe. Wire bonding is a process where wires, for instance copper or gold wire, are bonded on electrical contacts on the semiconductor die and corresponding carrier in order to electrically connect the components. Thereafter, the semiconductor die is encapsulated with molding compound to form a semiconductor package and then each package is singulated to separate it.
Traditionally, wire bonders have used single bond heads due to simplicity of implementation. However, U.S. Pat. No. 6,749,100 entitled “Multiple-Head Wire-Bonding System” reveals a wire bonding apparatus with multiple bond heads. Such a wire bonding apparatus enables bonding of multiple electronic devices on a wire bonding machine with a smaller footprint as compared to having separate machines. At the same time, it offers greater productivity. However, such a machine gives rise to more demanding handling needs due to the merging of multiple bond heads onto one platform.
One example is the loading of electronic devices to the bonding apparatus for bonding and unloading of the same after bonding. Conventionally, an input magazine is mounted on a loader side of the bonding apparatus for feeding unbonded electronic devices and an output magazine is mounted on an unloader side of the bonding apparatus for storage of bonded electronic devices after bonding. This is illustrated in U.S. Pat. No. 6,045,318 entitled “Lead Frame Supplying Method and Apparatus”. Electronic devices are introduced from one side of the bonding apparatus to a bonding tool, and after bonding, it is moved to the other side of the bonding apparatus to be unloaded. Although this set-up is straightforward and convenient for a bonding apparatus with a single bond head, it is not useful for a bonding machine with multiple bond heads since the electronic devices will either have to pass through another bond head to get to the other side of the bonding machine, thereby disrupting bonding at the other bond head, or take a longer route to bypass the other bond head, which greatly increases complexity and traveling time.
To avoid the aforesaid problems, it would thus be desirable to have separate input and output magazines that are both located on one side of a bonding apparatus. However, the conventional way of orienting the storage slots or feeding passages of the magazines in parallel with a conveying track of the bonding apparatus takes up considerable space when two magazines are placed side-by-side at the end of the conveying track. Moreover, since the conveying track is generally stationary, further space is required to move the two magazines sideways relative to the conveying track to respectively feed unbonded electronic devices or receive bonded electronic devices. Since the magazines are quite large in order to store multiple electronic devices, they might encroach into the space already occupied by other components of the bonding machine due to the sideways motion. It would be advantageous if the two magazines are arranged in another orientation that avoids the magazines being obstructed by other components of the bonding machine.
There are also certain electronic devices introduced for semiconductor integrated circuit packaging which have large bonding areas as compared to conventional ones. These electronic devices have a length in an x-axis that is parallel to the direction in which they are moved along the conveying track, and also a width in a y-axis perpendicular thereto. A difficulty arises if the y-axes of the electronic devices are longer than typical electronic devices. Whilst there is generally no problem in handling their lengths in the x-axis since the conveying track is operable to index the whole x-axis of the electronic device for bonding, to be able to bond the whole electronic device in the y-axis, a positioning table with a longer y-axis table range would be required. To design a positioning table with a longer y-axis table range would increase the moving mass of the positioning table and decreases productivity. It may also increase the footprint of the bonding machine to cater to the increased range of movement. It would be advantageous if the bonding machine could be designed to automatically bond the required surface area of the larger electronic device without the need to increase the y-axis table range of the positioning table.